1. Field of the Invention
This invention relates to printing systems in general, and more specifically to a merging type of printing system which utilizes an electronic buffer having sections containing text data which is to be merged automatically during printout. The text contained in one of the sections is merged with the text in the other section under the control of switch codes recorded and stored along with the text stored in the sections. Operation and hold flags input to the buffer are the addresses of the location of the present text and the next text in the other section defined by the switch codes.
2. Description of the Prior Art
The prior art devices include the Magnetic Tape "Selectric"* Typewriter. One of the problems encountered when utilizing a single tape Magnetic Tape "Selectric"* Typewriter (MT/ST) is that when a revision is to be made, the revision cannot be more extensive than the original recording or the previously recorded material will be overrun. This problem was alleviated on the MT/ST by providing a second tape and transferring the contents of the original tape to the second tape along with revisions (insertions and deletions) performed during the transfer. FNT *Registered Trademark, International Business Machines Corporation
However, the problem of addressing blank blocks on the tape for insertion of data is still present. Also, during scanning, the encounter of blank positions requires time for reading or special logic to skip these blank positions. The present invention, although functionally similar to the two station MT/ST, improves on the MT/ST system in that due to the structure of the dynamic shift register, the data is packed so that no blank spaces in text are present. In addition, the memory cycle is very short, and therefore, the data in the buffer can be readily scanned such that correction of improperly recorded material is easily handled.
Also, for further background of systems control and associated usage of electronic shift registers, referenceis made to copending U.S. patent application Ser. No.'s 104,888; 158,346, and 158,347; now U.S. Pat. Nos. 3,675,216; 3,753,239; and 3,781,813, respectively, all assigned to the assignee of this application.